The lamellarins are polyaromatics alkaloids originally isolated from marine sources and comprising a fused polyaromatic framework. The family of lamellarins are constituted by two basic structures:

Both structures have a pyrrolic ring substituted with aryl units. The hexacyclic structure 1 is a 14-phenyl-6H-[1]benzopiran[4′,3′,4,5]pyrrolo[2,1-a]isoquinolin-6-one. Depending of the substituents and the presence of a double bond between C8-C9 the members of this family are designed with different letters.
 R1R2R3R4R5R6R7R8AOCH3CH3CH3HCH3CH3HOHCOCH3CH3CH3HCH3CH3HHEOHCH3CH3CH3HCH3HHFOHCH3CH3CH3CH3CH3HHGHHCH3CH3HHCH3HIOCH3CH3CH3CH3CH3CH3HHJHHCH3CH3CH3CH3HHKOHCH3CH3HCH3CH3HHLHHCH3CH3HCH3HHSHHCH3HHHHHTOCH3CH3CH3CH3HCH3HHUHCH3CH3CH3HCH3HHVOCH3CH3CH3CH3HCH3HOHYHCH3HCH3HCH3SO3NaHZHHCH3HHHCH3HβHHHCH3HHHH
 R1R2R3R4R5R6R7BOCH3CH3CH3HCH3CH3HDHHCH3HCH3CH3HHHHHHHHHMOHCH3CH3HCH3CH3HNHHCH3CH3HCH3HWOCH3CH3CH3CH3HCH3HXOHCH3CH3CH3HCH3HαHCH3CH3CH3HCH3SO3Na
R. J. Anderson et al, J. Am. Chem. Soc. 1985, 107, 5492, describes the isolation and characterization of four polyaromatic metabolites, the lamellarins A-D, obtained from a marine prosobranch mollusc Lamellana sp. The structure of lamellarin A was determined by an X-Ray crystallographic study and the structures of lamellarins B-D were assigned by interpretation of spectral data.
N. Lindquist et al, J. Org. Chem. 1988, 53, 4570, describes the isolation and characterization of four new lamellarins: E-H from the marine ascidian Didemnum chartaceum obtained from the Indian Ocean. The structure of lamellarin E was determined by an X-Ray crystallographic study.
A. R. Carroll et al, Aust. J. Chem. 1993, 46, 489, isolated six new lamellarins: I, J, K, L, M and the triacetate of the lamellarin N, and four known of this type: A, B, C, and the triacetate of lamellarin D, isolated from a marine ascidian Didemnum sp.
S. Urban et al, Aust. J. Chem. 1994, 47, 1919 and Aust. J. Chem. 1995, 48, 1491, described the isolation and characterization of four new lamellarins, O, P, Q, R, with the substructure type 2 from the marine sponge Dendnilla cactos. Later S. Urban et al, Aust. J. Chem. 1996, 49, 711, described the structure of lamellarin S from the ascidian Didemnum sp.

M. V. R. Reddy et al, Tetrahedron 1997, 53, 3457, isolated five new lamellarins: T, U, V, W, and X, and the first example of sulfated lamellarin, Y, isolated from the marine ascidian Didemnum sp obtained from the Arabian sea.
R. A. Davis et al, J. Nat. Prod. 1999, 62, 419, described one new lamellarin, Z, and various examples of sulphated lamellarins isolated from the marine ascidian Didemnum chartaceum. 
M. V. R. Reddy et al, J. Med. Chem. 1999, 42, 1901, isolated a new lamellarin, α, isolated from the marine ascidian Didemnum sp.
Finally, J. Ham et al, Bull. Korean Chem. Soc. 2002, 23, 163, described the isolation and characterization of the lamellarin β obtained from a marine ascidian Didemnum sp.
Lamellarins C and D have been shown to cause inhibition of cell division in a fertilised sea urchin assay, whereas lamellarins I, K, and L all exhibit comparable cytoxicity against P388 and A549 cell lines in culture. Recently, lamellarin N has been shown to exhibit activity in lung cancer cell lines by acting as a Type IV microtubule poison.
Furthermore, J. L. Fernández-Puentes et al, PCT Int. Appl WO 97/01336, describe that these compounds have also cytotoxic activity on multidrug resistant cells as well as efficacy as non-toxic modulators of the multidrug resistant phenotype and, therefore, afford an attractive potential source of chemotherapeutic agents.
The limited availability of natural material has resulted in the search for alternative synthetic methods being sought for the natural compounds and related analogs. M. G. Banwell et al, Int. Patent Appl. WO 98/50365 and Int. Patent Appl. WO 99/67250 described the synthesis of lamellarin K via 1,3-dipolar cycloaddition between an alkyne and an N-ylide of isoquinolin.
Lamellarin G trimethyl ether was also synthetised by S. Ruchirawat et al, Tetrahedron Lett. 2001, 42, 1250. The synthesis involved the formation of the core pyrrolo[2,1-a]isoquinoline, followed by the formation of the lactone ring.
Lamellarins I and K (1) were obtained by L. Castedo et al, Synlett 2001, 7, 1164, by a new approach based on the 1,3-dipolar cycloaddition of a nitrone to an alkyne. The key cycloaddition yield an isoxazoline which rearranged to afford the central pyrrole ring.
F. Albericio et al, Org. Lett 2003, 5, 2959, has described a total solid-phase synthesis of Lamellarins U and L.
Ishibashi F. et al., J. Nat. Prod., 2002, 65, 500-504 describe the synthesis and structure activity relationship for some lamellarin derivatives.
The discovery of the main target for an anticancer agent is an essential element to better understand its mechanism of action and to guide the development of clinically useful analogs. To illustrate this, one can refer to camptothecin (CPT) discovered in the early 1960s but successfully developed only a quarter of a century later when its main, and perhaps unique, molecular target was identified: topoisomerase I. The observation in 1985 that CPT stabilizes DNA-topoisomerase I complexes provided the starting point for the rational development of safe CPT analogs which culminated in the mid 1990s with the approval of topotecan and irinotecan for the treatment of ovarian and colon cancers.
The search for non-CPT topoisomerase I poisons has been very active for the past ten years but only a limited number of potent topoisomerase I poisons has been discovered.